I have copied your vectors from clipboard. What I did to achieve what you want:

# remove SLB.Close, which is the first element of the vector.
#It might not be the case for your actual vector though.
SLB_buy<-SLB_buy[-1]
# remove the dates and transform in numeric
SLB_buy<-substring(SLB_buy, 11)
SLB_buy<-as.numeric(SLB_buy)
# depending on your actual vector the position to start substring
#(in this case 11) might vary.